The present invention relates to a bookmaking apparatus in a bookmaking system. More specifically, the bookmaking apparatus aligns sheets printed by an image forming apparatus into a bundle on a tray in the proper page order and binds the sheet bundle to create a booklet. The bookmaking apparatus may belong to an image forming apparatus, such as a printer, printing machine or copier, as well as belonging to finishing apparatus of an image forming apparatus equipped with the same.
Generally, this kind of apparatus is widely used as a terminal device of an image forming apparatus such as a printer or printing machine, to stack sheets formed with images in page order, then after aligning the sheets into a booklet, a bookmaking system applies adhesive to one edge of the stacked booklet and binds the booklet to a cover sheet.
Of particular note, there are systems that can print a predetermined booklet by printing predetermined information such as on-demand printing and automatically bind and cover the booklet, cutting the edges of sheets to finish the booklet.
As an example of such a system, the Japanese Patent Publication 2004-209869 discloses a system wherein sheets output from an image forming apparatus are received from a discharge outlet and guided to a discharge path. The sheets are then stacked and stored in a tray equipped at a lower side of the discharge outlet. The sheet bundle stacked on the tray in a horizontal posture is turned 90 degrees and is then guided to an adhesive application unit in a substantially vertical posture for gluing.
The glued sheet bundle is then folded around, and glued to, a cover sheet supplied by an inserter. After being glued, sides of the sheet bundle not glued are trimmed to finish the booklet. The finished booklet is then stored in a stacker.
As further disclosed by the reference, sheet bundles from an image forming apparatus are stacked in a substantially horizontally posture in a tray, and the edges of the sheets in the tray are aligned to a correct posture to form a sheet bundle. This sheet bundle is turned 90 degrees to be glued in a vertical posture, then joined with a cover sheet to form a finished booklet. The sheet bundle is then trimmed by a cutting device. This kind of system is well known in the art.
As disclosed by the reference, there are many systems that arrange a discharge path and stacking tray in a substantially horizontal direction, and comprise an adhesive application unit, a cover sheet binding device and cutting device on a conveyance path in a vertical direction. After turning the sheet bundle stacked in a horizontal posture to be vertically oriented, the edges of sheets, i.e., the binding, aligned in a bundle are applied with adhesive. This binding portion is then aligned to a center of a cover sheet and bound. After covering the booklet, the other edges of the sheet bundle are trimmed by the cutting device, and then the sheet bundle is sequentially stored in a stacker.
In an apparatus not limited to the above apparatus, a problem may exist when conveying a sheet bundle stacked on a tray to a predetermined subsequent processing position using gripping conveyance means. Specifically, during the conveyance of the sheet bundle from the tray position to the subsequent processing position, the sheet bundle can become skewed or otherwise become out of registration, even if the sheet bundle is correctly aligned, and adhesive or other processes are applied to an edge of the sheet bundle.
A problem of precision may be caused by rattling of components in the conveyance mechanism, e.g., the gripping means that grip the sheet bundle on the tray as described above, or rattling when driving a rack and pinion or belt by a drive mechanism in order to guide the gripping means to engage a guide rail arranged in a direction to convey the gripping means. Particularly, because there is backlash in the rack or movement of the timing belt in driving, no matter how well sheets are aligned and orderly maintained on the tray, the sheet bundle itself may become misaligned or skewed, resulting in an unavoidable problem due to a lack of precision.
Therefore, the present invention provides a sheet conveyance apparatus that can convey a sheet bundle in a correct posture to a correct position by establishing posture correction means in the conveying of a sheet bundle, aligned on a tray, to a finishing position separated from the tray. Furthermore, the present invention provides a simple and low-cost mechanism that corrects the posture of a sheet bundle.